Environmental Detective Case Studies

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Date:

📚 Part 1: Read the Cases & Choose

Read the short case studies below.

Case A — Muddy River (Stream near town)
Local residents report fewer fish and cloudy water since a new subdivision started 6 km upstream. After rain, sediment coats rocks. Water temperature is about 14°C.

1. For Case A, which is the most likely immediate cause of the cloudy water?

Algal bloom caused by warm water

Increased sediment from upstream construction

Introduction of invasive fish species

A natural seasonal drop in oxygen

Case B — Park Trees
Several large trees in the town park have yellowing leaves and dead patches near the base. After rain, small puddles show a rainbow sheen and there are new car parks beside the grass.

2. The rainbow sheen in puddles most likely indicates which pollutant in Case B?

Road salt

Petrol or oil runoff

Fungal infection of roots

Natural tannins from leaves

Case C — Beach Erosion
A popular sandy beach has lost dunes and the shoreline has a steep drop. Locals say a new seawall was built 2 km along the coast last year. Storms have been stronger in recent seasons.

3. Which human activity is most likely contributing to the beach erosion in Case C?

Planting native dune shrubs

Construction of a seawall up the coast

Reducing boating in the area

Installing sand ladders for access

Case D — Farm Stream Pollution
A small stream beside a dairy farm shows nitrate levels above safe guidelines. Cows graze within 10 m of the stream and a manure heap sits on compacted soil. Local water temperature is 12°C.

4. What is the most likely source of the high nitrate levels in Case D?

Runoff from fertiliser or manure

Increase in sunlight causing plant decay

Introduction of trout into the stream

Lower rainfall this season

✏️ Part 2: Matching & Short Answers (Detective Strategies)

5. Match each detective strategy (left) with its primary purpose (right). Draw lines between matching items.

A. Test water samples for nitrate, turbidity and pH

B. Survey shoreline photos over time with a drone

C. Inspect nearby vehicle parks and check for oil stains

D. Walk transects to record vegetation cover and soil loss

1. Identify long-term changes in dune shape and sand loss

2. Confirm chemical sources affecting aquatic life

3. Find evidence of surface pollutant spills from cars

4. Measure how vegetation loss relates to erosion

6. For Case A (Muddy River): List two tests or measurements an environmental detective should do to confirm sediment is from the construction site upstream.

7. For Case D (Farm Stream): Propose one practical change the farmer could implement to reduce nitrate runoff. Explain briefly.

8. For Case B (Park Trees): Outline a simple three-step detective plan to identify and stop the pollutant harming the trees.